The present invention concerns a process for the continuous manufacture of form-stable rod-shaped elements from interlocked and interbonded filamentary and/or fibrous material; a system for the performance of such process; cigarette filter units manufactured by such process; and applications of the process.
There is a known process for the manufacture of form-stable rod-shaped elements of interlocked and interbonded filamentary and/or fibrous material wherein a continuous strand of fibrous material is impregnated with a plasticizer serving as a binder and, in conjunction with compaction of the strand material, is drawn through a steam-heated nozzle. In the latter operation, the non-enveloped outside of the strand slides directly along the inside of the nozzle. However, the pull necessary a draw the strand through the nozzle involves an undesirable reduction of the curl of the filaments or fibres and, accordingly, of the stability of the so manufactured rod against radial deformation. In another known process, the non-enveloped strand passes through a funnel, in which it is sharply compressed, and thence passes to a conveyor on which it is enveloped and pressed to the form desired. As the strand, before passing to the conveyor, is drawn through the funnel, this process also involves an undesirable stretching of the strand.